Describe with neat sketch pressure & temp. compensated flow control valve.

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written 7.0 years ago by

teamques10 ★ 70k

• modified 7.0 years ago

Schematic diagram of a pressure and temperature compensated flow-control valve is shown in Fig.
Its operation is essentially same as the restrictor type, pressure compensated flow control valve in association with a throttle type temperature compensating device. In the compensatory spool, the pressure is sensed to the bottom of the spool through a passage drilled in its body, instead of having a separate sensing passage.
In order to attain balance position, the compensatory spool moves and adjusts the area of metering orifice.
This gives necessary pressure compensation.
Also instead of using the usual throttling arrangement, a cup shaped device with “V” notches is used for better control on flow rate. This cup is held by a small spring against the shoulder of an aluminium alloy rod which extends through the cup into the oil flow. It is set for a particular flow rate. As temperature of oil rises, the oil becomes a little thinner and tend to flow faster through.
However, the increased temperature also causes the Aluminium rod to expand and close the throttle opening to compensate for the change in oil viscosity. Thus even with the thinner oil, the flow rate stays essentially the same.
A check valve is frequently incorporated to allow relatively unrestricted reverseflow.

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